The College of Optometrists

What do most people consider to be a significant rise in IOP post-dilation? I was taught that a rise of 5mmHg or more was enough to send the patient to casualty. On many elderly patients that I dilate I find that a rise in IOP of 5mmHg-ish is not at all unusaul.

there is no cut and dry answer - it depends on all the factors. However,30 is regarded by many to be glaucoma -

So it depends on as near to 30 it rises too.

Usually, the pressure drops slightly as the iris takes up less volume when dilated.

5 rise is unusual and if there was other factors - then to casualty they would go!

But I would not send every tom dick and harry with a 5 rise. They could report back in 2 hrs for recheck, if there was no other factors. Dilation is not a big deal - and a pressure rise is not a frightening issue. (hey - do you ask abt allergy to drops before instillation? - should you know!)

We had one today - old boy, on steroids, two brothers with glaucoma (poag) - small pupils. VH = grade 3 (open), bscked up with pentorch nazal shaddow - wide open angles. Starting pressures 18. After half hr 30+ pressures. Noted assymetric disks with some superior pallor. Sent to casualty as suspect sub acute and also management (ie pilocarpine to get the presures down). ( with my mild cautious referal letter) palf

I'm wondering about situations where there are no other risk factors. If the pressures seem to have gone up post dilation then I'll recheck them. Sometimes I doubt the tonometer. In some places I've worked the tonometer has been less than reliable. I'm fearful of the situation where a patient comes in for a sight test, asymptomatic and just wanting a new pair, and ends up in casualty. How do you word it when you explain to them whats going on and why?

The old adage is if you dilate & induce an acute angle closure your are doing the patient a favour i.e a provocative test which reveals underlying pathology. I have never come across one in my career & dilated thousands, probably tens of thousands.

two points DD

1) if you go to different practices ie as a locum - you have poor patient care in the longer term. How can you take responsibility for a dilation ? I would preach a very cautious approach. (2) if you can't rely on practice tonometry - wouldn't it be ethical to get your own - a 2nd hand perkins hardly costs a days wage for a locum - and might save a complaint. A workman is only as good as his tools! As a locum you should never bite off more than you can comfortably chew, and also weigh up the risks carefully, remember Murphy's Law and act on that!!

2) if you are properly prepared in yr mind how to proceed - a routine dilation is not a big deal. Yr px will understnad, if you don't frighten him to death by tales of searing pain etc. It is no bigger deal than a corneal ulcer or a ret detatchment. These only become disasters if not managed properly. As michel says you are doing the bloke a favour. Early on in my career I missed a narrow angle (I didnot dilate) - a month later the px told me that shortly after my test she had acute glaucoma and lost the eye. Imagine how I felt! palfina

Doing the patient a favour?? That depends greatly upon what investigations/precautions you took b4 you decided to put tropicamide in their eyes.

Hi Hamy,

With respect, you didn't believe what I said. Read the figure, thousands, dilated & NO angle closure induced,as far as I am aware, it's as rare as a nun in a brothel. If it did THEORETICALLY happen, provided your records were clear about the circumstances I repeat, you are doing the patient a favour, albeit unpleasant for them as they are obviously potential angle closure victims. Look at what palfi says. I NEVER tell the patient I'm instilling drops, I just do it. I usually instill proxymet first (I do applanation tonometry) & then Tropicamide ( the proxymet speeds up absorption of the mydriatic) The worst that can happen is that they rub their eyes & give themselves an abrasion. In 30 + years of practice I have never known anyone come back with this, & I repeat again I've never knowingly had an angle closure. BALANCE the patient benefits against the theoretical risk & go for it.

Buy a gonio lens and then it wouldn't be a problem! You can also measure the A/C depth if your slit lamp is up to it.

Mydriasis induced sub acute angle closure is NOT rare as a "nun in a brothel", you just need to know when to look for it and to educate your patients about the symptoms.

Angle closure WITH pupil block is more lightly to occur when the pupil is mid dilated for a prolonged period usually as the mydriasis is wearing off (ie several hours later). Where as angle closure WITHOUT pupil block or Plateau Iris occurs as the pupil dilates to the maximum diameter (20-30 mins after instillation). In cases where you suspect angle closure with pupil block may occur, the recovery time can be reduced by using the minimal mydriatic. Additionally, this approach will also benefit those with plateau Iris as the maximal pupil diameter will not occur.

I tend to use G.Tropicamide 0.5% and G. Phenylepherine 2.5% routinely but only G.Tropicamide 0.5% if I'm concerned of the possibility of post mydriatic IOP elevation. Then recheck IOPs 1-2 hours after. Personally, I would only refer to casualty if the IOPs remain over 30mmHg after that time (assuming they where fairly normal to start with). I would suggest a rise of 6 to 8mmHg is worth rechecking and anything over 10mmHg is worth referring (by Goldmann tonometry, NCT is too variable for this) even if it recovers as this could be happening each time the Px is in the dark. Also, do not be lulled in to a false sense of security is the Px already has PIs, sometimes they aren't big enough and there may be a persistent element of pupil block (in the HES I do this deliberately to ensure the patentcy of PIs). If this occurs refer for enlargement of the PIs.

I think the approach of not telling patients that you are going to dilate their pupils probably isn't acceptable in this day & age. Possibly the reason michel le curie hasn't had a case of sub acute angle closure is be cause the patient doesn't realise it's happening?

Having said all that, the benefits of mydriatic fundus examination far out weigh the risk of angle closure and anyway if the angles are that narrow it will occur sooner or later so it may as well be in a controlled environment with a professional that knows what to do!

Just my pennys worth.